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6 MEASUREMENT - TAKING READINGS
Disclaimer: Inherent in ultrasonic thickness measurement is the possibility that the instrument will use the
second rather than the first echo from the back surface of the material being measured. This may result in
a sound-velocity reading that is HALF what it should be.
Responsibility for proper use of the instrument and recognition of this phenomenon rests solely with the user
of the instrument.
Other errors may occur from measuring coated materials where the coating is insufficiently bonded to the
material surface. Irregular and inaccurate readings may result. Again, the user is responsible for proper use
and interpretation of the measurements acquired.
6.1 BEFORE YOU START
•
Prepare the surface - see "Condition and Preparation of Surfaces" on page 24.
•
Set the zero point of the transducer - see "Setting up the Gauge" on page 7.
•
Select units; press
6.2 PROCEDURE
1. Apply couplant
For the gauge to work correctly there must be no air gap between the transducer and the surface of
the material to be measured. This is achieved using a couplant.
Before the transducer is placed on the surface, put a small amount of couplant on the surface of the
material. Typically a single drop is sufficient.
13
to select metric (mm) or imperial (inches).
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